Want to replace a hdd in a Dvr was told that you can't use a regular hhd that you have a hdd made for Dvr.Is this correct?

As far as I'm aware they are standard hard drives with the software loaded. :shrug:

So any off the shelf hdd will work as a replacement in a dvr.

It really depends on the DVR. For example, I know the older Integral boxes will not recognize any drive except Western Digital or Maxtor.

You might check with the MFG first.

Thanks Jeff which brings me to another does this apply to severs.Are severs hhd different from a desktop hdd?

Some DVRs have a limitation on the size of the drive. You also should determine is it is an IDE drive, or SATA. I would think that any 7200 RPM drive would be good. Seagate SV35 series drives are specifically designed for DVRs - https://www.seagate.com/www/en-us/products/consumer_electronics/sv35_series/

What is the information stamped on the drive that is in it now and why are you replacing it?

Typically "yes" they're different but in ever-changing times what used to always be IDE in a desktop is now changing to almost everything SATA.

Servers typically were always (Wide)SCSI...now they're moving to SAS or in cheaper-end servers or when large amounts of storage are needed without tons of extra cost, also SATA.

As Bobby mentioned, let us know what the drive's label has on it and we can help you out a lot easier.

Some of the PC based DVRs (PCs with a PCI recording card) limit the amount of storage the recording software will interface to with license keys. This kept you from getting a base model and adding storage much cheaper than what they would sell it to you for.

I would call the manufacture and discuss with them. If the DVR is still under warranty it won't be after you crack that box. Always helps to ask the people that make it first! If it is was made by a reputable manufacture they will likely be more than happy to assist you.